1. Field of the Invention
The present invention relates to an information processing apparatus that controls the use of composite contents data formed of multiple content data in accordance with usage rules for each content data, and a method and a computer program product for processing such contents.
2. Description of the Related Art
As the contents business becomes diversified and goes online, more flexible digital rights management (DRM) has been requested. For example, the content data are separated from usage rules that describe the usage rules for the content data, thereby offering a contents protecting system that can control the use of the contents in an adaptable manner. Moreover, ISO/IEC 21000 (MPEG-21), which is targeted at distribution and management of various digital contents, includes standards of the rights expression language REL (hereinafter, “MPEG-21 REL”) that flexibly describes usage rules.
The use of the composite contents data formed of multiple content data for which usage rules are defined, such as of edited literary works and quoted works, is controlled by the usage rule of each of the content data. However, when the content data have a nesting structure and the usage rule of a superordinate content data differs from the usage rule of its subordinate content data, the verification result on the use of one content data may conflict with the verification result on the use of another content data.
For example, the usage rule of the top content data, which indicates the entire composite contents data, may permit general users to browse the contents, but the usage rule of its subordinate content data, which is a component of the top content data, may permit only limited users to browse. In such a case, the verification on the use differs depending on the authorization given to each user. Furthermore, the usage rule of the top content data may permit printing and browsing, but the usage rule of its subordinate content data may permit browsing only. Then, the verification of the use differs depending on how the contents will be used. In such a situation, the usage control intended by the creator of the composite contents data may be unable to perform.
Various methods have been suggested to solve the above problem. For example, U.S. Pat. No. 5,638,443 discloses two controlling modes using “strict rule” and “more lenient rule” to solve the conflict as described above.
By the “strict rule”, the use of a content data is permitted only when the same usage rule is satisfied for all of the superordinate content data and subordinate content data of the content data. In other words, if the content data include a single material that is denied, the use of the entire composite contents data is denied.
By the “more lenient rule”, when the composite contents data is to be used, the control is performed in a manner to permit the use of content data of the composite contents data that satisfy the usage rule only.
According to the technology described in U.S. Pat. No. 5,638,443, however, the above control method cannot be explicitly designated as a usage rule, and thus the method is applied independently of the usage rule defined by the usage rule. For this reason, the use permitted to the user changes in accordance with the control method. Then, the control may deviate from the usage rule intended by the contents provider such as the creator of the composite contents data or the creators of the content data.
For example, the composite contents data may include some content data that are intended to be widely distributed, but there may be a strict rule for the use of the edited work of these materials (composite contents data). Then, in a system operating in accordance with the “strict rule” controlling method, the usage rule for the entire composite contents data is applied, which strictly limits the use of the content data. This would limit the opportunity of using the materials, on the contrary to the original intention of the creators of the materials. On the other hand, in the same situation with a system operating in accordance with the “more lenient rule” controlling method, the intention of the creator of the composite contents data wishing to protect one's creation as an edited work may not be carried out.